instmctions): The function of the Animal Core is to produce and maintain all of the animals required for the scientific projects for this and several other program project grants. The specific services of the Animal Core personnel include 1) Providing the highest quality animal and veterinary care, 2) Breding of transgenic and knockout mice, 3) Performing experimental inoculafions, bioluminescent imaging, neurologic scoring of animals, and fissue collecfion, 4) Transportafion of animals and tissues between the laboratory and the animal facility, 5) Producfion of antibodies in mice for experimental use, 6) Performing microinjection of constructs to generate new transgenic lines, 7) Providing cryopreservation of the various mouse lines. The Animal core will perform bioassay experiments in support of all three projects in addifion to the Science core. Samples from the Animal core will be supplied to the Neuropathology core for analysis, and direcfiy to the Projects. The Animal Core operates in two purpose-built facilifies in the Hunters Point area of San Francisco, approximately 7 miles from the main UCSF campus. Its activifies are directed by Dr. Prusiner and Dr. Pierre Lessard, a laboratory animal veterinarian. Building 830B is a nine room transgenic mouse breeding facility that houses our large breeding colony. Building 830 houses all the experimental animals in 21 rooms, under BSL-2 and 3 biocontainment. It houses on average 20,000 mice, 250 hamsters, and 8 rabbits. The facility is inspected annually by USDA, and bi-annually by UCSF/IACUC. RELEVANCE (See instructions): Understanding the molecular pathogenesis of prion diseases is central to ultimately developing treatments for a range of neurodegenerative disorders. This Animal Core supports the projects by performing bioassay studies, and the maintence of animals for other core funcfion such as anifibody producfion.